1. Field of the Invention
Aspects of the invention can relate to an electro-optical device with a reduced cross-talk, a driving method of the electro-optical device, a driving circuit of the electro-optical device, and an electronic apparatus.
2. Description of Related Art
Related art liquid crystal display devices using a liquid crystal as an electro-optical material, which are an example of electro-optical devices, have been widely used, as display devices taking the place of cathode ray tubes (CRT), for display units of various data processing instruments, liquid crystal televisions, and the like.
Such related art liquid crystal display devices can include an element substrate provided with pixel electrodes arranged in a matrix shape and switching elements, such as TFT (Thin Film Transistors) connected to the pixel electrode, a counter substrate on which a counter electrode opposing the pixel electrodes is formed, and a liquid crystal as an electro-optical material filled between both substrates.
The TFT is turned on by scanning signals (gate signals) supplied through scanning lines (gate lines). In a state where the switching elements are turned on by application of the scanning signals, image signals of voltages corresponding to gray scales are supplied to the pixel electrodes through data lines. Then, electric charges corresponding to the voltages of the image signals are accumulated in the pixel electrodes and the counter electrode. Even when the scanning signals are removed and the TFT is turned off after accumulation of the electric charges, the accumulated state of electric charges in the electrodes is maintained by the capacitance of a liquid crystal layer or storage capacitors. In this way, when the switching elements are driven to control the electric charges to be accumulated in accordance with the gray scale, the alignment state of the liquid crystal is varied every pixel, the light transmittance is changed, and thus the brightness can be changed every pixel. Accordingly, the gray-scale display is possible.
However, in the liquid crystal display device, for example, decomposition of liquid crystal components and contamination due to impurities in liquid crystal cells occur by application of a DC component of the applied signal, so that phenomena such as blots of a displayed image take place. Therefore, an inversion driving method of inverting the polarity of the driving voltage of the pixel electrodes, for example, in a unit of frames of the image signal is performed in general. A surface inversion driving method is a method of inverting the polarity of the driving voltage at a constant cycle in a state where the driving voltages of the entire pixel electrodes constituting an image display area are set to the same polarity in a screen.
Considering the capacitances of the liquid crystal layer and the storage capacitors, the application of electric charges to the liquid crystal layer of each pixel may be performed only during a partial period. Therefore, when a plurality of pixels arranged in a matrix shape is driven, a scanning signal is simultaneously applied to the pixels connected the same scanning line through the scanning line, an image signal is supplied to the pixels through the data lines, and the scanning lines supplying the image signal are sequentially shifted. That is, in the liquid crystal display device, when the scanning lines and the data lines are common to a plurality of pixels, a divisional multiplex driving method is possible.
In this way, in the liquid crystal display device, the driving voltage can be applied to the pixels only in a partial period in consideration of the capacitance. However, the potentials of the data lines have an influence on the pixel electrodes due to the combined capacitance and the leakage of electric charges even during the period when the TFT is turned off. The potential variation of the applied voltages to the pixels makes the display in a screen irregular and particularly makes the deterioration of image quality visible in intermediate gray-scale areas.
Therefore, in order to prevent such problems, in the liquid crystal display device, an inversion driving method, which combines, for example, a line inversion driving method changing the polarity of the driving potential in a unit of lines with an inversion driving method in a unit of frames, is employed. By changing the polarities of the image signals transmitted through the data lines for a relatively short time, influences of the combined capacitance and the leakage of electrical charges can be reduced.
However, in the line inversion driving operation, an electric field (hereinafter, referred to as a transverse electric field) between pixel electrodes adjacent to each other in the column direction or the row direction, in which voltages having different polarities are applied, on the same substrate is generated. Further, in a dot inversion driving method of changing the polarities of the driving voltages in a unit of dots, a transverse electric field is generated between the pixel electrodes adjacent to each other in the column direction and the row direction in which voltages having different polarities are applied.
When such a transverse electric field is generated between the adjacent pixel electrodes, one edge side portion of each pixel electrode is influenced by the transverse electric field, so that the inclination direction of the liquid crystal molecules can be easily different from that of other liquid crystal molecules. Due to the disturbance in alignment (disclination) of the liquid crystal molecules, a stripe shape (stripe blur) appears along the portion having the defective alignment. That is, light leakage occurs in the disclination area, and when the disclination area is made to be a non-open area, the aperture ratio is reduced.
Japanese Unexamined Patent Application Publication No. 5-313608 suggests, as a technique for preventing the disclination due to the transverse electric field and securing uniformity of an image, a technology that one horizontal period is divided into a first period and a second period, the image signal is applied to the pixel electrodes during the first period by supplying the driving pulse to the scanning lines and supplying the image signal to the data lines, and the image signal having a polarity opposite to the previous one is supplied to the data lines without supplying the driving pulse to the scanning lines during the second period. However, in this technology, there is a problem that the time period which can be used for the pixel writing becomes a half a normal time period, thereby causing the insufficient writing.